Abstract
Fluctuation in food resources for and crop damage by, Greater White-fronted Geese are discussed in relation to the modernization of farming in northern Miyagi Prefecture, Japan, during 30 years from 1975 to 2005 during which the population of geese has increased. Rapid changes in government policy designed to cut back rice cultivation, has reduced the total area of rice fields by 30%, while the percentage of improved large fields with efficient drainage systems has increased some 30-61% between 1975 and 2005. The rise in the number of large fields has led to reaper machinery being replaced by combine harvesters. Combine harvesters produced twice as much waste grain as reapers during the period from 1975 to 1995. The size of soybean fields, another changing crop in the region, has also increased since the late 1990s. The total volume of food resources for wild geese (including waste rice, wheat, barley and soybean) increased between 1975 and 2005. Changes in the utilization of agricultural land have produced temporal and spatial changes in the foraging distribution of geese, and in crop damage, since 2000. Damage to wheat and barley crops has occurred as a result of considerable depletion of waste rice and soybeans by foraging of geese. At the same time, however, the accumulation of goose droppings has helped raise levels of soil inorganic nitrogen, which helps grass to regenerate. It is possible to manage the goose population so as to benefit agriculture. In this paper we demonstrate the impact of changes in agriculture on the Greater White-fronted Goose population in Japan and stress the need to monitor human activity in order to conserve the geese.
